With the development of integrated circuit technology, semiconductor device elements and structures have become increasingly smaller in size. In order to reduce the parasitic capacitance between the metal interconnects, low-k dielectric materials are gradually used instead of silicon dioxide in the interconnect structure. A porous ultra-low k material can further reduce the dielectric constant of the dielectric material in the interconnect structure. Therefore, porous ultra-low k materials are generally used in interconnect structures in small-sized semiconductor devices.
An opening needs to be formed by etching the porous ultra-low k material prior to forming the metal interconnect. The uniformity of the opening affects the uniformity of the metal interconnect.